Parents and immediate family of monks and Candidates may visit their son up to four times a year, though not during the seasons of advent or lent. A monk may write to his family ("Snail mail") once a month, except during the penitential seasons mentioned above. In some cases, the monk may call his parents once a month in place of writing.
Regarding contact with friends, it is left to the superior's discretion, but it is generally more limited than contact with immediate family.